Contract lawyer and adjunct Penn law professor Ken Adams has a great post over at his AdamsDrafting blog on the fondness for "tested" contract language, in preference to drafting new, explicit language. He does a nice job of filleting the argument for such "tested" phraseology in a lot of cases.

Just to pile on, there are two other potential problems: (a) the likelihood that a court will later change its mind about what that language means when it surveys the landscape again after a few years, and (b) the likelihood that a court will let in parol evidence (see the previous post!) to show that these two particular parties really, really meant something different than what other people meant when they used the same language. That latter risk is much more formidable if the parties have used a piece of complex off-the-shelf boilerplate that if they wrote their own explicit language.